Reconstructing the Cenozoic provenance evolution of Mallorca (Balearic Promontory): insights from detrital zircon U-Pb and (U-Th)/He double-dating

The Balearic Promontory (BP) is a NE-SW oriented continental block located in the centre of the Western Mediterranean that corresponds to the northern prolongation of the Betic-Balearic front. The BP represents a unique case study, as it records two distinct compressive periods from the Alpine orogeny, as well as exhibits evidences of volcanism and back-arc extension related to the opening of the Western Mediterranean. Mallorca is the only island of the BP that preserves an almost complete Cenozoic sedimentary record, which encompasses a significant shift in the geodynamic evolution, evolving from northern derived deposits during the Paleogene (“Catalanide-Pyrenean”) to a southern source area during the Early Miocene (“Betic”). As both source areas currently correspond to marine basins, the Cenozoic detrital deposits therein represent the only remnants whose provenance study can contribute to decipher the hinterland tectonic evolution. Nevertheless, the majority of these deposits are carbonate-dominated, and thus, techniques such as detrital geochronology and thermochronology may prove useful in instances where traditional provenance analysis are challenging. The present study seeks to provide a new perspective on the provenance evolution of Mallorca for the first time from two different timings and settings. By using detrital zircon (DZ) double dating we characterized the Paleogene and Neogene provenance and exhumation history. Our findings suggest an evolution from predominantly Mesozoic-derived DZ during the Paleogene, to a mixed Mesozoic and late Palaeozoic DZ during the Neogene. The presence of only two Eocene ZHe ages in early Miocene DZ may suggest a gradual exhumation process within the hinterland rather than a fast dismantling related to the “Betic” compression. Furthermore, the identification of Oligo-Miocene aged zircons related with synsedimentary volcanism enabled us to establish a maximal depositional age (MDA) for some samples, thus providing a more precise chronostratigraphic constraint.